A body, moving at 20ms accelerates uniformly at 2 for 4 seconds. It continues the journey at this speed for 8 seconds, before coming to rest seconds at tseconds after with uniform retardation. If the ratio of the acceleration to retardation is 3 : 4 (a( sketch the velocity - times graph of the journey (b) find t (c) find the total distance of the journey
Explanation
(a)
(b) If we let r be the retardation, then : r = 3 : 4 when simplified, r = Velocity after 4 seconds = 20 + x 4 = 30ms So that : = t = 9 seconds
(c) The total distance of the journey = {[ (20 + 30)4] + (30 x 8) + (30 x 9)} = 100 + 240 + 135 = 475 metres
